Where federated search is carried out there is typically a need to merge search results received from different search engines that may retrieve information from different sources. For example, federated search can be carried out at a search portal which receives a search query and sends that to a plurality of different search engines. It collects the results and typically provides a user interface whereby the collected results may be accessed. The process of sending the query to the different search engines and receiving the results occurs automatically without the need for user input and may be carried out “behind the scenes” so that the user may be unaware that it is occurring.
In this way, federated search portals are currently used to search many different public sources of information, such as by using Internet search engines, public databases and other public data collections. However, many enterprises, educational organizations, and other entities have access to information sources which are not public. Issues then arise as to how to appropriately provide federated search where at least some of the information sources are public and at least some are not.
Existing federated search systems often simply collect lists of results obtained from different information sources without providing any additional “intelligence” in the way the results are presented. For example, in some federated search systems the portal provides a user interface means whereby the end user is required to manually merge, de-duplicate and sort the results lists from the different information sources. This is time consuming and complex and places undue burden on the end user. This is especially so where the end user is a novice or child with no knowledge even of the existence of the individual data sources being searched.
Other information retrieval systems are known whereby a user is able to operate a user interface in order to specify that a query is issued to a plurality of different sources that the user specifies. The raw results are received at the user interface and presented, often side by side, for the user to manage using tools provided as part of the user interface. This type of search is not automated in the same way as federated search, with the functionality being mainly provided at the user interface rather than at a separate federated search engine. Also, this type of search system is only suitable for expert users with detailed knowledge of the different information sources available.
The embodiments described below are not limited to implementations which solve any or all of the disadvantages of known information retrieval systems.